Pesticidal composition containing a synergistic combination of an oxazolo-pyridine thiophosphate derivative and cypermethrin

ABSTRACT

A novel pesticidal composition containing the synergistically effective active-substance combination comprising the compound: S-[6-chloro-oxazolo[4,5-b]-pyridin-2(3H)-on-3-yl-methyl]-O,O-dimethyl-thiophosphate or the compound: (CH 3  O) 2  P(S)--OCH═C(CH 3 )C(O)OCH 3  with the compound: 1(RS)-cis,trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropanecarboxylic acid-(RS)-(α-cyano-3-phenoxybenzyl) ester. 
     The compositions are used for the control of various pests. They are suitable in particular for controlling stored-food pests, granary pests and other storehouse pests of the orders: Coleoptera, Lepidoptera and Acarina. Also hygiene pests of the orders: Diptera and Blattaria can be successfully controlled with these compositions.

The present invention relates to a novel pesticidal composition containing as active ingredient an active substance combination, to the use thereof for controlling pests, especially insects, and also members of the order Acarina, and to the production of this composition.

The control of pests is now becoming increasingly difficult. Factors playing a significant part in this connection are on the one hand the build-up of resistance which the pests to be controlled exhibit against the pesticidal compositions being used, and on the other hand the contamination of the environment caused by the necessary increase of the applied concentrations of active substances. A reduction in the employed amounts of chemical substances must therefore be aimed at in order to avoid the disadvantageous consequences for the environment. However, the emergence of resistant species of pests is promoted by the use of lower active-substance concentrations which offer no guarantee of a complete destruction of the pest populations, including the development stages thereof.

To avoid these disadvantages, it is thus desirable for the control of pests, such as insects and Acarina, to provide compositions which are sufficiently effective even in small applied amounts, and which neither promote the development of resistance nor constitute a danger with respect to the contamination of the environment. Attempts have hence frequently been made to satisfy these requirements by the use of a combination of different substances for the purpose of utilising the potentiation effects thereby occurring. Mixtures of compounds from various classes of substances, for example pyrethrins, pyrethroids, carbamates and phosphoric acid esters, have already been described as synergistically effective preparations in the pesticidal field. It has however been shown that the known combination preparations do not in every case fulfill to the desired extent the demands made of them in practice, particularly with regard to effectiveness, toxicity and economy in application.

There has now been found a novel synergistically acting combination consisting either of the compound: S-[6-chloro-oxazolo[4,5-b]pyridin-2(3H)-on-3-yl-methyl]-O,O-dimethyl-thiophosphate of the formula I ##STR1## or of the compound: (CH₃ O)₂ P(S)--OCH═C(CH₃)C(O)OCH₃ of the formula II ##STR2## and the compound: 1(RS)-cis,trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropanecarboxylic acid-(RS)-(α-cyano-3-phenoxybenzyl) ester of the formula III ##STR3## which combination exhibits a broad spectrum of biocidal activity, and which can be incorporated for use into novel compositions according to the invention.

The substance of the formula III is a mixture of cis and trans isomers, and the ratio of cis to trans forms can be high or low.

The active-substance combination according to the invention is used for the control of various pests. It is suitable in particular for controlling stored-food pests, granary pests and other storehouse pests of the orders: Coleoptera, Lepidoptera and Acarina. Also hygiene pests of the orders Diptera and Blattaria can be sucessfully controlled.

The individual components of the active-substance combination according to the invention are known as pesticides, and can be produced by known methods. The compounds of the formulae I and II are described in the German Auslegeschriften Nos. 2,131,734 and 2,119,488, and are known under the designations of Alfacron® and Damfin®, respectively, whilst the compound of the formula III is published under the name of Cypermethrin in the Pesticide Manual, 6th Edition, 1979.

The range of 5000:1 to 1:1 applies with regard to the determining weight ratios of the compounds I to III in the compositions according to the invention. The combination ratio in the range of 1500:1 to 1:1 is especially suitable for inducing the synergistic effect, and within these limits, the range of 300:1 to 1:1 is particularly effective.

The range of 3500:1 to 1:1 applies with regard to the determining weight ratios of the compounds II to III in the compositions according to the invention. The combination ratio in the range of 1000:1 to 1:1 is especially suitable for inducing the synergistic effect, and within these limits, the range of 500:1 to 1:1 is particularly effective.

Instead of being used as component in the compositions according to the invention, the inventive active-substance combination can also be used on its own. The proportion of the active-substance combination in the compositions according to the invention is 1 to 90% by weight, used together with 99 to 10% by weight of carriers and formulation auxiliaries.

The invention on which the compositions according to the invention are based is further illustrated by the following Examples. The biocidal activity of the active-substance combination is determined by means of the topical application method, and the potentiation effect is ascertained therefrom.

EXAMPLE 1

Forty flies (Musca domestica ♀♀) of a homogeneous population of the highly-resistant strain R-300 were dorsally treated by application in each case of 1 μl of an acetonic active-substance solution per ♀ fly. Ten individuals were placed together with a cotton wool pad soaked with hydromel into each of a number of Petri dishes (9 cm in diameter) at room temperature. An evaluation was made after 24 hours by ascertaining the percentage mortality rate. This procedure was carried out separately for each individual active-substance component and combinations thereof. By application of a logarithmically graduated concentration series, there were obtained increasing mortality values from which, with the Probit Analysis according to Finney.sup.(1), a dosemortality straight line was calculated. The LD₅₀ values were determined in this manner.

Evaluation

On the basis of these values, the potentiation rate (PR) was ascertained as a measure of the occurring synergism by means of the Cotox formula.sup.(2). The potentiation rate (PR) is given from the following quotient: ##EQU1## In this quotient, LD₅₀ represents the value of the active-substance combination measured in the toxicological test, whilst LD₅₀ denotes the expected value of the combination which is obtained by the following equation: ##EQU2## The values μA and μB signify the proportion of the respective mixture component in the total mixture. PR values of >1 indicate potentiation between the mixture components.

                  TABLE 1                                                          ______________________________________                                         Results                                                                        Active sub-                                                                    stance or                                                                      active-sub-                                                                            Weight ratio LD.sub.50 ng/♂*)                                     stance  of the       calcu-          Cotox                                     mixture mixture      lated   found   coefficient                               ______________________________________                                         comp. I --           --      7509    --                                        comp. II                                                                               --           --      14527   --                                        comp. III                                                                              --           --      51.6    --                                        comp. I/                                                                               1000:1       6587    2567    2.6                                       comp. III                                                                              145:1        3759    1037    3.6                                                30:1        1344     467    2.9                                       comp. II/                                                                              1600:1       12300   6133    2.0                                       comp. III                                                                              280:1        7254    2654    2.7                                                60:1        2650    1150    2.3                                       ______________________________________                                          *Musca domestica, strain R 300 (highlyresistant)                         

The mutual potentiation of two active substances can also be represented graphically according to Loewe and Muischnek.sup.(1). In this case, the LD₅₀ values of any given mixture ratios are ascertained by means of an isobole, that is, a curve of equal toxic effect. With additive effect of the combination components, all LD₅₀ values move along a straight line. When potentiation occurs, however, this curve deviates in the form of a hyperbola from the straight line, the deviation increasing with the degree of potentiation.

According to Table 1, the mixture ratios of compound I/compound III=145:1 and of compound II/compound III=280:1 constitute preferred embodiments of the present invention.

The active-substance combinations on which the compositions according to the invention are based are used according to the invention together with suitable carriers and/or additives. Suitable carriers and additives are solid or liquid and correspond to the substances common in formulation practice, such as natural or regenerated substances, solvents, dispersing agents, wetting agents, adhesives, thickeners and/or binders.

For application, the active-substance combinations are processed according to the invention into the form of dusts, emulsion concentrates, granulates, dispersions, aerosols, sprays, solutions or suspensions. Furthermore, aqueous preparations or concentrates of the active-substance combinations are used according to the invention for cattle dips and spray races, and also in the pour-on method, the hand-spray method and the hand-dressing method.

The compositions according to the invention are produced by intimate mixing and/or grinding of the active-substance combinations with suitable carriers, optionally with the addition of dispersing agents or solvents which are inert to the active substances. The active-substance combinations can be obtained and used in the following forms: solid preparations: dusts, scattering agents and granulates; liquid preparations:

(a) water-dispersible concentrates of active-substance combinations: wettable powders, pastes and emulsions;

(b) solutions.

The content of an active-substance combination in the preparations described above is between 1 and 90% by wt.

EXAMPLE 2 Emulsion concentrate

20 parts by weight of an active-substance combination are dissolved in

70 parts by weight of xylene, and to this solution are added

10 parts by weight of an emulsifier consisting of a mixture of an arylphenyl polyglycol ether and the calcium salt of dodecylbenzenesulfonic acid.

Water can be added in any proportion to the emulsion concentrate to form a milky emulsion.

EXAMPLE 3 Emulsion concentrate

5 to a maximum of 50 parts by wt. of an active-substance combination are dissolved at room temperature, with stirring, in

30 parts by weight of dibutyl phthalate,

10 parts by weight of solvent 200 (low-viscous, highly aromatic petroleum distillate),

15 to 35 parts by weight of Dutrex 238 FC (viscous highly aromatic petroleum distillate), and to this solution are added

10 parts by weight of an emulsifier mixture consisting of castor oil polyglycol ether and the calcium salt of dodecylbenzenesulfonic acid.

Milky emulsions are formed by adding water to the emulsion concentrate obtained.

EXAMPLE 4 Wettable powder

5 to 50 parts by weight of an active-substance combination are vigorously mixed, in a mixing apparatus, with

5 parts by weight of an absorbent carrier (amorphous silicic acid or Wessalon S) and

55 to 80 parts by weight of a carrier (bolus alba or kaolin B 24), and a dispersing agent mixture consisting of

5 parts by weight of a sodium lauryl sulfonate, and

5 parts by weight of an alkyl-aryl-polyglycol ether.

This mixture is ground in a dowelled disk mill or airjet mill to a particle size of 5-15 μm. The wettable powder thus obtained gives a good suspension in water.

EXAMPLE 5 Dust

5 parts by weight of an active-substance combination are thoroughly mixed with

2 parts by weight of a precipitated silicic acid, and

92 parts of weight of talcum.

The compositions according to the invention are particularly suitable for controlling stored-food pests and granary pests, because these compositions satisfy to a great extent the requirements necessary for the protection of stored foodstuffs. They are thus distinguished by having the following properties: low lethal minimum concentration for pests (especially for resistant forms), low toxicity to humans and to productive animals, uniform duration of effect over several months, and no residue problems.

By virtue of these properties, it is possible to successfully control with the compositions according to the invention the following typical stored-food pests, granary pests and other storehouse pests:

    ______________________________________                                         Oryzaephilus       saw-toothed grain beetle                                    surinamensis                                                                   Trogoderma         khapra beetle                                               granarium                                                                      Lasioderma         cigarette beetle                                            serricorne                                                                     Chryptolestes      flat grain beetle                                           ferrugineus                                                                    Stegobium          bread beetle                                                paniceum                                                                       Necrobia           copra beetle                                                rufipes                                                                        Anthrenus          carpet beetle                                               vorax                                                                          Sitophilus         grain weevil                                                granarius                                                                      Sitophilus         rice weevil                                                 oryzae                                                                         Sitophilus         maize weevil                                                zea mais                                                                       Rhizopertha        lesser grain borer                                          dominica                                                                       Acanthoselides     common bean weevil                                          obtectus                                                                       Sitotroga          grain moth                                                  cerealella                                                                     Nemapagon          European grain moth                                         granellus                                                                      Tyrophagus         foodstuff and feed mite                                     putrescentiae                                                                  Acarus siro        flour mite                                                  Ephestia           flour moth                                                  kuehniella                                                                     Araeocerus         coffee-bean weevil                                          fasciculatus                                                                   Carpophilus        dried fruit beetle                                          hemipterus                                                                     Tenebrio           yellow mealworm                                             molitor                                                                        Tribolium          red flour beetle                                            castaneum                                                                      Tribolium          black-brown mealworm                                        destructor                                                                     Tribolium          confused flour beetle;                                      confusum                                                                       and also the cockroaches:                                                      Phyllodromia       German cockroach                                            germanica                                                                      Periplaneta        American cockroach                                          americana                                                                      Blatta             Russian cockroach                                           orientalis                                                                     ______________________________________                                    

A further important aspect of the present invention is that the compositions of the invention can be successfully used also against hygiene pests, such as flies and fly larvae, as well as against mosquitoes and mosquito larvae; and they thus make a significant contribution towards the preservation of the health of humans and animals by preventing the spread of disease. Furthermore, the yield of productive animals is considerably improved by the use of the compositions according to the invention in agriculture. 

What is claimed is:
 1. A composition for control of insects and acarids which comprises an insecticidally and acaricidally effective amount of a mixture of (i) S-[6-chloroxazolo[4,5-b]pyridin-2(3H)-on-3-ylmethyl]-O,O-dimethylthiophosphate and (ii) α-cyano-3-phenoxybenzyl 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate in a weight ratio of from about 2000:1 to about 6:1 in a carrier therefor.
 2. A composition according to claim 1 wherein said ratio is from 1000:1 to 30:1.
 3. A method of controlling insects and acarids which comprises applying thereto or to the habitat thereof an insecticidally and acaricidally effective amount of a mixture of (i) S-[6-chloroxazolo[4,5-b]pyridin-2(3H)-on-3-ylmethyl]-O,O-dimethylthiophosphate and (ii) α-cyano-3-phenoxybenzyl 3-(2,2-dichlorovinyl)-2,2-dimethylcylopropane carboxylate in a weight ratio of from about 2000:1 to about 6:1.
 4. The method according to claim 3 wherein said ratio is from 1000:1 to 30:1. 